what list comprehension can't

[ajikoe]

Hello,

Can we impose if then else into list comprehension ?
Like we do in lambda-map form:

This code change None into 0
L = [None, 12]
R = map(lambda x: (x==None and [0] or x)[0], L) # [0,12]

pujo

[Devan L]

I wasn't aware that python supported "if then else".

[Christophe Delord]

Hello,

On 24 Jun 2005 11:45:14 -0700, aj****@gmail.com wrote:

Hello,

Can we impose if then else into list comprehension ?
Like we do in lambda-map form:

This code change None into 0
L = [None, 12]
R = map(lambda x: (x==None and [0] or x)[0], L) # [0,12]

Do you mean:
[(x==None and [0] or [x])[0] for x in L]
or [{None:0}.get(x,x) for x in L]
or [x or 0 for x in L]

Well, the third solution doesn't exactly fit the specification but may
be easier to read.
Christophe

[ajikoe]

Thank you

pujo

[Steven D'Aprano]

On Fri, 24 Jun 2005 21:04:15 +0200, Christophe Delord wrote:

Hello,

On 24 Jun 2005 11:45:14 -0700, aj****@gmail.com wrote:

Hello,

Can we impose if then else into list comprehension ?
Like we do in lambda-map form:

This code change None into 0
L = [None, 12]
R = map(lambda x: (x==None and [0] or x)[0], L) # [0,12]

Do you mean:
[(x==None and [0] or [x])[0] for x in L]
or [{None:0}.get(x,x) for x in L]
or [x or 0 for x in L]

Well, the third solution doesn't exactly fit the specification but may
be easier to read.

Or, more generally,

[0 for x in L if x is None]

which doesn't solve the asked-for question, but is a useful feature.
--
Steven.